Apparatus for inhibiting tar polymerization



Jan 16, 1940.a

A. CIBULKA El AL APPARATUS FOR INHIBITING TAR POLYMERIZATION Filed Jan.31, 1936 rqn. uns E; E; Z5 magali 27 44 J JTIA M INA Patented Jan. 16,1940 time rarest ries APPARATUS FOR INHEBTING TAR ?GLYMERZATKN AloisCibulla; Highlands, and Maurice W. Mayer,

Baytown, Tex., assignors to 'Standard @il Development Company, acorporation of Delaware Application .lanuary 3l, 1936, .Serial No.61,776

1 illaim.

This invention relates to improvements in the heat `treatment ofhydrocarbon oils in which polymerization of the separated from the oilduring vaporization is inhibited.

"" It has been customary in the cracking ci petroleum oil to subject theoil :in a coniined zone to elevated temperatures and pressures, afterwhich it has been passed to a digestion zone where thermo-decompositionoi' the oil has oc- 1D curred. The thus treated oil has been conductedfrom the 'digestion zone to a tar separator in which the oil ismaintained quiescent to permit separation iromthe oil of tar formedduring `decomposition of the oil. The tar has lbeen mainili tainedexposed to the full heat oi the' main body of oil in the tar separatorthroughout `the period of separation, with a result that a high rate ofpolymerization of 'the tar to form coke has occurred.

'20 It is an object of this invention to minimize form, used for examplein the tube and tank method 'of cracking petroleum oil. Tar formed bythe pyrogenetic decomposition of the oil settles in the separator i. Thetar as it settles is conducted directly to a tar pot t lconnecteddirectly to the bottom wall of the separator l.

In the embodiment illustrated, the Atar pot 3 comprises a container theupper portion i of which is provided with a radially extending liange 5,which is secured to a similar iiange t carried by a tubular extension idependent from the bottom wall of the separator i. The tubular extensionl can be approximately 2li inches in diameter. The base I!) of thecontainer i? is provided with a bottom closure l2 secured to a flange lion the hase of the container. The container 3 is provided with a tubularmember i5 protruding outwardly from an intermediate portion of thecontainer 3. The tubular member i5 is closed by a tubular extension il.Member l5 and extension Il are provided with radially extended ilangesi3 and I9 respectively, whereby they are secured to gether. into thecontainer. The container 3 is of lesser diameterthan the tar separatorl. l

The level of tar is maintained at `an intermediate postion in the tarpot 3 through they Tar as it separates in separator l falls,

(C1. Mii-58) following arrangement of parts. Discharge line 25 leadsfrom the bottom Wall i2 lof the tar pot 5. The discharge line isprovided with =a fluid pressure valve 2l. Valve 2l is a diaphragmcontrol valve compri-sing a diaphragm 29 which extends f5 transverselyacross a fluid tight casingll. The valve 2l is connected by means of apiston 3l with the `diaphragm 29. The valve 2l is normally maintainedclosed by means 'of a helical spring 32. The valve 2 is actuated bymeans of l0 compressed air, Aor other iiuid, in a Way to be laterdescribed.

The level of tar in the tar pot 3 is controlled by a float 37, whichrests upon the surface 33 oi' theta-r. The lloat 3l is attached to oneend of a -16 rod itil, the opposite 'end of which carries .arm ti whichis pivotally mounted in the extension il.

Rise or fall of 'the float 3l with rise or fall of the level of tar inthe tar pot 3, therefore, causes rotary movement ofthe arm it. Thisrotary move- 20 ment of the arm M is caused to control the lsupply ofair to actuate the valve 2l, as follows; An air line 44 leading to thecasing it of the vdiaplfuagrn valve 2l is connected to la pilot valve46. The pilot valve Mi, which is of well known 25 construction, isprovided with a trigger Eil mounted for reciprocaticn longitudinally toopen or close the pilot valve. Rotation of the arm di iscaused to eiectlongitudinal reciprocation of the trigger-5t, as follows.' A crank arm52 is 30 radially connected to the arm Ill. An adjustable linkli isconnected at one end to the crank arm 52 in spaced relation to the armlll. The opposite end of' the link et is pivotally connected to a lever5S, an intermediate portion of which is 35 pivotally supported at 5l.The lever 55 carries a head mounted for engagement with the trigger 5Bto effect longitudinall reciprocation of the trigger 5B with change inlevel of the tar 38. Thevtar is maintained at the low level desig- 4Qnated 38 in the tar pot-in order that the interfacial surface Will berelatively small, and any given surface quantity oi liquid tar may bemaintained in direct Contact with the vapors in the separator E for avery small length of time. 45 This feature permits of considerablecooling of the tar without appreciable condensation of cycle fractionswhich are in the vapor state. It will be notedk that as the liquid level38 rises the diaphragm valve 2l is caused to be open to allow 50 the tarto iiow out through the line 25.

The polymerization inhibiting pot is provided with a plurality ofvertically spaced valve sample lines 63, 64, t5 and 66, which connectwith a manifold 51. A valve line 68 leads from the 55' manifold 6T,whereby samples of the contents of the polymerization inhibiting pot canbe withdrawn for inspection. A valved line 99 and a valved line 69a areprovided to admit cold iuX to the tar pot for flushing purposes whennecessary. The iiux may be admitted to the tar pot at a temperature of'700 F. or lower, to aid in inhibiting polymerization of the tar and,therefore, minimize the formation of coke. The valved line 69aspecifically performs the function of cooling the pivot 4I in order tominimize the formation of coke at this point as well as aiding inreducing the temperature of the tar within the pot 3.

By the procedure described, the tar level is maintained in a relativelysmall tar pot of, for example, 20 inches diameter, and the tar fallsdirectly as formed into the pot. A cylindrical screen l2 protrudes intothe ta-r separator I from the tar pot 3, to prevent coke, concrete orthe like, from falling from the separator I into the pot 3. The upperend of the tubular screen 'l2 is preferably open. The time that the tarmust remain at the high temperature in the separator equipment isreduced and, therefore, the amount of polymerization of the tar to formcols-.e is decreased. Coke formation at the bottom of the separator I isalmost completely eliminated.

By holding the liquid within the pct 3 and exteriorly of the separatorI, the surface of liquid tar in direct contact with the vapors in theseparator I is very small. In View of the small interfacial surface, thecooling of the liquid with cold tar iiux reduces the polymerization ratewithout appreciable condensation of the heavier fractions in the vapor,and the tar gravity remains unchanged. The use of the particular form oftar pot illustrated provides an economical method of improving theoperation of cracking coil tar separator, since it is necessary onlythat a tubular extension 1, or nozzle, be driven into the bottom of theexisting separator drum and the tar pot attached thereto. Furthermore,the float device 3l can be easily installed and repaired through thelateral extension of the tar pot. The addition of the tar pot to anexisting separator and the maintenance of the control level in the potitself provides additional effective separator height, since the tarlevel is moved farther away from the vapor outlet nozzle leading fromthe separator I. While the device has been described as applied to aseparator used in the pyrogenetic decomposition of oil, it will beunderstood that it can be used in connection with any process for theheat treatment of oil in which tar is formed as a result of thetreatment, and some of the advantages of the invention will be retained.

Various changes and alternate arrangements may be made within the scopeof the appended claim, in which it is our intention to claim all noveltyinherent in the art as broadly as the prior art permits.

We claim:

An apparatus of the character described including a tar separatingchamber adapted to receive cracked hydrocarbon products, a separatesmaller tar pot secured to the bottom of said tar separating zone and incommunication with said tar separating chamber for receiving tar fromsaid tar separating chamber, said tar pot at its upper portion having asmaller cross sectional area than said tar separating chamber so that asmaller surface of the tar in said tar pot is exposed to the hightemperature in said tar separating chamber, said tar pot having a hollowlateral extension, means for maintaining the level of the tarsubstantially constant at a relatively low level in said tar pot and ata substantial distance below said tar separating chamber, said meansincluding a discharge valve for withdrawing tar from said tar pot, saiddischarge valve being operated by means responsive to the changes in thelevel of the tar in said tar pot, level responsive means including afloat arm pivoted in said lateral extension at a point removed from saidupper portion of said tar pot, and means whereby a cool fluxing agent isintroduced into said lateral extension of said tar pot adjacent saidnoat arm pivot for cooling and iushing said pivot and for cooling thetar without appreciable condensation of the vapors above the tar in saidtar pot. said smaller tar pot providing means whereby the time ofcontact between the tar in said tar pot and hot vapors in said tarseparating chamber is relatively short and the rate of polymerization ofthe tar is reduced.

ALOIS CIBULKA. MAURICE W. MAYER.

